1. Field of the Invention
The present invention relates to lawn and garden implements such as tillers, mowers, and snow throwers, particularly those having an engine-driven transaxle for driving ground engaging wheels.
2. Description of the Related Art
Prior lawn and garden implements, for example, mowers, tillers and snow throwers, conventionally have an engine and a transaxle individually mounted to a frame, to which a handle is also attached. The frame is ordinarily unique to the particular implement, and may comprise a portion of the working device, which may be, for example, the deck or sickle bar assembly of a mower, the cultivating blade assembly of a tiller, or the auger assembly of a snow thrower. Consequently, for a manufacturer to accommodate the production of a variety of such prior implements, substantial tooling and facilities expenditures, as well as high variable costs associated with inventory and production control, may be incurred. Further, the consumer must purchase, store, and maintain separate and complete prior implement units, one for each particular task.
One solution to these problems is to provide an implement having interchangeable working devices, which provides the capability for the implement to alternately be a mower, a snow thrower, a tiller, a chipper/shredder, a sweeper, or other types of implements.
One such implement is a two-wheeled tractor manufactured by BCS America, Inc. of Matthews, N.C., which includes a transaxle to which a horizontal shaft engine is attached at one end thereof, and to which one of a plurality of interchangeable working devices may be attached at the opposite end thereof. The transaxle drives wheels located on its opposite sides, between the engine and the working device. A handle is attached to the transaxle, and may swing around same such that one of the engine and the working device is selectively disposed beneath the handle, at the end of the transaxle where the operator is located. The other of the engine and the working device is disposed at the end of the implement opposite that at which the operator is located. A problem with this design is that, because one of the engine and the working device is disposed beneath the handle and near the operator, the operator has minimal clearance space for walking behind the implement, or must stand a substantial distance away from the implement, making maneuvering of same more difficult. Additionally, when the working device is disposed at the rear of the implement, the working device is disposed close to the operator, who walks behind the implement. Depending upon the type of working device used, this could possibly present a dangerous condition. For example, the foot of the operator may contact the working device, which may have a moving blade, and become injured. Further, having the engine so near the operator is also undesirable because the engine emits exhaust and substantial heat while running. Moreover, having the engine or the working device so near the legs of the operator may adversely affect the operator""s positioning, and impair the operator""s ability to control the implement. It is desirable to provide an implement which includes one of a plurality of interchangeable working devices and which overcomes the above-mentioned concerns associated with previous such devices.
U.S. Pat. No. 5,971,881, issued Oct. 26, 1999, and assigned to the assignee of the present application, is expressly incorporated herein by reference, and discloses a transaxle which may be attached to an engine to form an engine and transaxle module, which engine and transaxle module may be assembled into an implement; however, this patent does not disclose that one of a plurality of interchangeable working devices may be connected to the engine and transaxle module.
Additionally, manually maneuvering a prior implement such as a snow thrower, for example, as might be commonly done while the snow thrower is in its unpowered state inside a garage, generally requires that the transaxle be placed in neutral before pushing or pulling the implement about. Such maneuvering can be done more easily if the snow thrower has a transaxle equipped with a pair of axles joined through a differential gear, which allows the two axles to rotate at different speeds, such that turns may be made without skidding the tires. Providing a transaxle with a differential gear set to join the two axles can contribute significantly to the cost of a transaxle however, and additionally requires a differential lock to prevent one of the wheels from slipping during operation, with the other wheel receiving little or no power. Without a differential lock, which adds cost and complexity to the transaxle, the implement may be rendered immobile for lack of traction at one of its wheels during operation.
Most prior implements thus have relatively inexpensive transaxles including a solid axle which extends from opposite sides of the transaxle housing. Such transaxles ensure that both wheels will be powered during operation but, if the wheels are rotatably fixed to the axles, manual maneuvering of the implement may be difficult because the wheels cannot rotate relative to one another. This can make maneuvering difficult because at least one of the tires will tend to skid or slide during turns, requiring much more effort to push or pull the implement.
The wheels of some implements, such as snow throwers, are often attached to the axles through removable shear pins which extend through aligned cross bores provided in the wheel hubs and the ends of the axle. To better facilitate manual maneuvering of a snow thrower having a solid axle, the shear pins are removed, the wheels are moved axially inward along the axle, and the shear pins are replaced through the cross bores in the axle. The wheels are now free to rotate relative to the axle, and the annular ends of the wheel hubs axially abut the shear pins to prevent the wheels from slipping off the ends of the axles. To reestablish driving connection between the transaxle and the wheels, the shear pins are removed from the axle cross bores, the cross bores of the wheel hubs and axle are realigned, and the shear pins are reinstalled therethrough, allowing the transfer of torque from the transaxle to the wheels through the shear pins. Although removable shear pins are useful for preventing damage to the transaxle, the engine which powers the transaxle and/or the coupling mechanism therebetween, it is inconvenient to remove and reinsert the shear pins, as described above, to merely manually maneuver the snow thrower about more easily. An inexpensive and simpler to use means for facilitating easy manual maneuvering of an implement which does not have a differential gear set, is thus desirable.
Further, it is well known in the art that implements having relatively high centers of gravity have a greater tendency to tip over vis-a-vis those having lower centers of gravity. Often, the transaxle contributes significantly to the mass of the implement, and thus it is desirable, in an effort to provide a more stable implement, to lower the center of gravity of the transaxle, thereby lowering the center of gravity of the implement as a whole.
In overcoming the above-mentioned problems associated with prior art implements and transaxles, the present invention provides an implement having an engine and transaxle module, including an engine having an output shaft and a transaxle having an input shaft, the engine and the transaxle rigidly and directly attached to one another in a vertically stacked orientation. The engine output shaft and the transaxle input shaft are operatively coupled through a flexible drive member, whereby the transaxle is driven by the engine, and the transaxle has at least one output shaft for driving ground engaging wheels. One of a plurality of interchangeable working devices is attached to the engine and transaxle module.
Various working devices may be interchangeably attached to the engine and transaxle module to comprise various implements, thereby providing a consumer with a single implement base to maintain and store. The implement base includes the engine and transaxle module, power transmission means between the engine and transaxle and between the module and the working device, ground-engaging wheels, and perhaps a single handle. The working devices are attached to the engine and transaxle module of the base to suit the task at hand, whether it be mowing, tilling, snow removal or transporting earth or debris, for example.
The implement can be, among other types, a tiller, rotating blade or sickle bar mower, snow thrower or powered barrow, the working device of which is directly attached to the engine and transaxle module, as is the handle for controlling the implement. The inventive engine and transaxle module and, in some cases, the handle, is interchangeable between various types of these implements, thereby reducing unique tooling and attendant facility requirements, as well as associated inventory and production control costs.
Additionally, the present invention provides an implement which is relatively easy to manually maneuver, and which includes an engine having an output shaft, a transaxle having an input shaft and a pair of axially aligned axles, the axles being selectively coupled together, wherein, when the axles are coupled together, the wheels are rotatably fixed together, and when the axles are not coupled together, the wheels are free to rotate relative to each other. The implement may be a snow thrower having an auger assembly connected to one of the engine and the transaxle, the auger assembly operatively coupled to one of the engine and the transaxle.
The vertically stacked orientation of the engine and transaxle allows both the engine and the transaxle to be located in front of the handle and on the opposite side thereof from the operator, which provides more room for the operator to walk behind the implement, and also decreases the distance between the center of gravity of the implement and the operator, thereby making maneuvering of the implement easier, as well as obviating the above-described problems associated with having either the engine or the working device located beneath the handle on the operator side of the implement.
Additionally, the vertically stacked orientation of the engine and transaxle of the engine and transaxle module places the weight of both the engine and the transaxle more directly over the driving wheels, which advantageously affords better traction between the driving wheels and the ground surface.
In one form, the present invention provides an implement, including an engine and transaxle module, including an engine having an output shaft, a transaxle having at least one axle, the axle operatively coupled to the output shaft through the transaxle, the engine and the transaxle rigidly and directly attached to one another in a vertically stacked orientation; a handle attached to the engine and transaxle module; a ground engaging wheel operatively coupled to each axle; and one of a plurality of interchangeable working devices attached to the engine and transaxle module.
In another form, the present invention provides an implement, including an engine having an output shaft; a transaxle operatively coupled to the engine output shaft and having a pair of axially aligned axles, the axles being selectively rotatably coupled together; a working device being powered by the engine; a handle, movement of the implement being controlled by an operator through the handle; and a ground-engaging wheel connected to each axle, the wheels being rotatably fixed to one another when the axles are rotatably coupled together, the wheels being free to rotate relative to one another when the axles are not rotatably coupled together.
In another form thereof, the present invention provides a transaxle, including a housing; and a pair of axially aligned axles rotatably supported in the housing, the axles being selectively coupled together, the axles being rotatably fixed to one another when the axles are coupled together, the axles being free to rotate relative to one another when the axles are not coupled together.
The present invention also provides an implement having a relatively low center of gravity, the transaxle of which has a housing including first and second housing portions which interface substantially along a plane, but the shafts within the transaxle need not lie along this plane.
In still another form thereof, the present invention provides a transaxle, including a housing including first and second housing portions which interface substantially along a first plane; at least one axle rotatably supported by the housing; reduction gearing operably coupled to the at least one axle, the reduction gearing including two parallel shafts on which are disposed a plurality of gears, the shafts lying in a second plane, the first and second planes being nonparallel; and at least one bushing supported by the housing, the bushing including a pair of shaft retaining portions, each shaft retaining portion respectively supporting one end of each of the parallel shafts, the second plane extending between the shaft retaining portions.